Effects of environmental contaminants on the stress response of rainbow trout (Onchorhynchus mykiss) and brown bullhead (Ameiurus nebulosus)

Abstract

The accumulation of persistent contaminants is a significant issue for the health of aquatic environments. This study aims to determine the effects of polycyclic aromatic hydrocarbons (PAH) on the stress response of fish by monitoring plasma cortisol levels and the expression of key hypothalamic-pituitary-interrenal (HPI) stress axis regulators. Injection of benzo(a)pyrene (BaP), a ubiquitous PAH, induced a differential dose- and time-dependentcortisol response in rainbow trout and brown bullhead. BaP exposure also elicited a species-specific transcriptional response at all levelsof the HPI axis.Similarly, the HPI axis response to a standardized emersionstressor revealed species-specific differences. In the field, exposure of different brown bullhead populations to sediment with complex PAH mixtures did not consistently affect cortisol levels and providedno evidence of genetic adaptation of the stress response. Thus, future studies are needed to bridge the gap in our understanding between the laboratory and field effects of PAHs on the stress response of fish.